I just bought an Maudio Duo.
I was surprised to see it has inside, INA163's, and a +/-15V power supply. Wow, good quality components. OK, there were some JRC 5532 opamps in there too, but overall very good.
Note that this thing is really only suitable for AC use, since it requires 9V *AC*. I'm guessing there is a voltage multiplier in there to get something suitable to power the 7815/7915 regulators.
So, where am I using this? I have a local club where I leave a set of SP C4, Maudio DUo, and a small computer. An "installed sound" setup for all to use...
Richard